The present invention generally relates to blind rivets and, more particularly, to pull-type blind rivets having a large secondary head.
A number of blind rivets have been manufactured that include a hollow rivet body with a flanged head on one end and an opposite open end. A mandrel is at least partially positioned within the hollow rivet body and includes an enlarged head positioned adjacent the open end of the rivet body. The rivet body may be inserted into openings formed into workpieces that are to be joined to one another. The flanged head of the rivet body is positioned in engagement with a surface of one of the workpieces. A nose piece of a rivet setting tool is placed against the flanged head of the rivet body. The rivet setting tool includes a mechanism for pulling the mandrel. As the pulling mechanism pulls the mandrel, a portion of the rivet body between the mandrel head and the workpieces is collapsed on the opposite side of the far workpiece to form a secondary head on the rivet body to secure the rivet to the workpieces. This process is generally known in the art as “setting” the rivet. The rivet setting tool continues to pull the mandrel until the mandrel breaks at a predetermined point and at a predetermined break load thus leaving a portion of the mandrel within the set rivet body. At this time, the rivet is secured in the opening of the workpieces with the flanged head of the rivet body against a surface of one workpiece facing the operator performing the rivet setting operation and a formed secondary head against a surface of the other workpiece remote from the operator that is usually termed the “blind-side” surface.
Pull-type rivets have typically been used to join thin, soft or fragile materials to one another where access to only one surface is available. For example, brackets have been attached to foam insulated panels and thin metallic sheets have been coupled to one another using blind rivets. Accordingly, it should be appreciated that the demands of these industries are varied and that the product construction may need to be adjusted to suit the different requirements of each joint to be created and to give a reliable setting in each case. For instance, it may be desirable to reliably position the larger secondary head closer to the mandrel head in one application while in another application it may be desirable to reliably position the larger secondary head adjacent the flanged head of the rivet body. This joint design flexibility and reliability is not presently available in the known blind fastener art.
In addition, many of the applications using blind rivets include exposure to the elements on occasions where the relative humidity of the environment is high. In these applications, it may be necessary to prevent ingress of moisture past the head of the rivet after it has been set. Joint deterioration and structural damage may occur if the moisture is allowed to travel past the flanged head of the rivet body. Accordingly, it may be beneficial to provide a blind rivet having a means for sealing the flanged head of the rivet body against the workpiece and for the retained mandrel to seal within the bore of the rivet body.
The blind rivet of the present invention includes a rivet body having a longitudinally extending indented groove. The groove may be formed to define different shapes to impart different rivet setting characteristics that may be varied to provide optimum fastening characteristics to a variety of joints in a number of industries. For example, the shape of the indentation on the rivet body may be varied to cause a portion of the rivet body to collapse and form the secondary head adjacent to the flanged head on the end of the rivet body. A differently shaped indentation formed on the rivet body causes the rivet body to collapse and form the secondary head near the mandrel head.
In another feature, the rivet body is formed prior to setting to have a barrel-shaped shank positioned between the flanged head and the open end of the rivet body. The barrel shape significantly lowers the initial upset load that is needed to commence formation of the secondary head.
Furthermore, the rivet may include four indentations or slots circumferentially spaced apart from one another on the hollow rivet body. In this manner, four collapsed legs are formed during rivet setting. By creating four legs instead of the three legs shown in the prior art, the setting load is lower and allows the potential use of higher strength rivet materials resulting in higher tensile and shear strength.
Additionally, the blind rivet of the present invention includes a feature where the mandrel is coupled to the rivet body to allow shipping and handling of the rivet prior to setting as well as providing a feature for maintaining a portion of the mandrel within the rivet body after the setting procedure has been completed. A plurality of indentations are formed in the rivet body such that portions of the rivet body are displaced into a recess or recesses formed on the mandrel adjacent the mandrel head.
In addition, the blind rivet includes a seal positioned between the flanged head of the rivet body and the workpiece to prevent ingress of moisture or contamination around the set rivet. The rivet is further sealed by retaining a portion of the mandrel with the hollow body and causing the flange of the rivet body to engage the mandrel and one or more grooves. Lastly, the rivet body flange may be shaped such that it may accept a cover or cap. The cap may be colored to match or complement the colors of the individual workpiece.